NAPA, Calif. -- DJ Hayden has been a constant observer at Oakland Raiders training camp. The surgically repaired stress fracture in his right foot has kept the cornerback from participating.

The No. 12 overall pick of the 2013 NFL draft underwent the procedure shortly after the Raiders' minicamp ended on June 19. And with recovery time from surgery to repair a stress fracture in the foot estimated between six and eight weeks, Hayden is about six weeks out.

Hayden is on the physically unable to perform list and coach Dennis Allen was asked Monday if he expected Hayden to be on the field before the end of the preseason, or if he was a candidate for the regular season PUP list.

"I expect to see him before preseason (ends)," Allen said, "but we’ll have to wait and see. He is getting better, but he is not ready to be out here playing football yet."

If Hayden does go on the regular-season PUP list, provided he remains on the preseason PUP list throughout, he must sit out at least the Raiders’ first six games.